To establish a close proximity wireless communication connection, it is generally necessary to match the transmission power of a signal to be transmitted from the transmission side with a signal level required by the reception side. There is provided the following method of matching the transmission power with the required signal level. That is, a connection request signal indicating that the transmission side requests connection is transmitted to the reception side with a minimum power, medium power, and maximum power in turn. The transmission side then extracts identification information included in a response signal from the reception side. The transmission side compares the extracted identification information with identification information registered in advance. If there is identification information matching the extracted one, communication is performed using a transmission power equal to that of the connection request signal.